"Stranger in a Strange Land"
The most hated hour of the series, and for good reason. The flashbacks—Jack travels to Thailand to “find himself,” shacks up with Bai Ling, forces her to ink him, gets beat up for it—are dreadfully boring, with the lamest excuse for character insight and backstory exposition yet. The island stuff is just as dull, but retrospectively it becomes infuriating, because it features as clear a sign as there is that Darlton indeed made shit up as they went along.
We’re introduced to an Other named Isabel, nicknamed the Sheriff for her high rank within the group and her execution of law and order. She’s there to decide whether Juliet is a traitor and blah blah blah. It doesn't matter because, although we’re told she’s oh-so important, this is the only episode she appears in. The writers' room basically created a character on the fly to serve the needs of the episode, and discarded her after the fact. She's never seen again, despite the ever-increased face time the Others receive in the back half of the season. How much stock can we put into a mythology that rewrites its own universe like this?